We have had a BK Sirocco 30 for 3 years and have always had a distinct smell when we turn it down low. After 2 years talking (complaining) to the dealer/installer, moisture testing every piece of wood, replacing the door seal, extending the flue, resealing the flue-fire join, a new unit was installed. The replacement has allowed us to control the heat slightly better but still smells if down low (4 o'clock or lower on t'stat). If we put our noses close to the unit when we first notice the smell we can detect it mostly through the thermometer hole. This seems the most likely place that air can escape, but theoretically if the cat is doing its job the only thing moving through there is water vapour, right? The cat always looks to be glowing and active when we're getting the smell. The upshot is we can never get an overnight burn because we can't turn it down low enough to last all night. I wonder how many other people's observations and troubleshooting matches our experience and if we should all be letting BK know the extent of the issue. Our fire is located in the lowest point in our house (2-storey and also 2 steps down to living room) and I wonder if this affects how much the smell moves upwards. Any confirmation or further advice much appreciated.